/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineUserInterface.h
Contacts server to obtain a user id from an arbitrary user-entered name string, eg. display name
true if the operation was started successfully
bool QueryUserIdMapping ( const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & UserId, const [FString](API\Runtime\Core\Containers\FString) & DisplayNameOrEmail, const [FOnQueryUserMappingComplete](API\Plugins\OnlineSubsystem\Interfaces\IOnlineUser\FOnQueryUserMappingComplete) & Delegate )